123 Amax accuracy issues

[molar]

molar:

Just hit me after I posted. AR Performance. Don't know much about them so can't really comment.

Normally when someone posts groups I ask if they are good at calling their shots. I trust what they are describing far more if they can tell me their call area and or that they called the shots. You would be amazed at how many guys have no clue what I am talking about,why, or how calling shots fits into the critical thinking process when it comes to marksmanship.

You don't need anything elaborate for the 120 Sierras. We used H 335, TAC, 2520, 8208, and I am sure CFE will do as well as the other powders so you don't need to spend more money on powder for that bullet. I like from 28 1/2 to 30 1/2 grains of 2520; 28 1/2 of TAC; 28 of 8208. Cant remember the load of H 335 but probably 28 grains. About any primer was fine.

The 107's are more particular towards powders from what I have experienced and also particular with jump. When I shot them competitively through a .260, I always had to seat them so they would touch the lands and for 600, I hard seated them. I never had an iota of luck with them with any of six or seven different Grendel barrels of varying lengths and styles over the years so I stopped shooting them. And the guys on the forum for the most part said they either didn't shoot well at all or were marginal. A few never seemed to have a bit of a problem with them no matter how they loaded them. Bill Waites is one of those guys. Of course since you bought some of them, test them since they offer the potential for decent velocities with the Grendel.

About the only thing constructive I may offer is to shoot at 200 or even 300 if possible. 100 just isn't far enough to show if you really have a big problem or not. My opinion only.

LR55

I've seen a 5 shot group posted by LRRPF52 that was shot with 107 Sierra's out of a Lilja barrel that was literally one ragged hole, but I don't recall what powder and charge he was using.

I found some 120 Nosler BT's at Cabelas today. I have high hopes for these. I don't think I've ever encountered a barrel that would not shoot ballistic tips well. Do you have load data for the 120 BT's using XBR 8028 and CFE 223? Nosler lists 27.5 as max for that bullet, but I can imagine one can go to 28.5

[rabiddawg]

Volume II Grendel Reloading Handbook has

6 loads with 8208 under a 120 nbt. Lowest is 27.5 gr up to 28.5.

1 with cfe223 31.0 gr.

[LR1955]

I've seen a 5 shot group posted by LRRPF52 that was shot with 107 Sierra's out of a Lilja barrel that was literally one ragged hole, but I don't recall what powder and charge he was using.

I found some 120 Nosler BT's at Cabelas today. I have high hopes for these. I don't think I've ever encountered a barrel that would not shoot ballistic tips well. Do you have load data for the 120 BT's using XBR 8028 and CFE 223? Nosler lists 27.5 as max for that bullet, but I can imagine one can go to 28.5

molar:

I don't shoot the Nosler BT's because I have a large amount of 120 Sierras.

I would avoid going over 28 grains of 8208 with a 120 or heavier bullet. Probably better for the 107's since my experience has been that you need to shoot them fast for them to shoot well.

One thing about the Grendel I won't do is go over a max charge. You won't get a increase in velocity that is large enough to make any difference in either efficiency or accuracy. We have found that in most cases guys seem to get the best performance when loading close to a max charge if that helps any. Exceeding recommended charges in a Grendel normally results in sheared bolt lugs and too much wear on the brass to be worth not very much gain in velocity.

LR55

[JASmith]

Getting molar's measure of lemgth needed to touch the loand will help clear up some, but not all the questions.

Did AR Performance indicate whether the chamber is the SAAMI chamber or one that will work "better than" the standard chamber?

If so, did the company provide reamer or chamber drawings for the finished barrel?

[molar]

Getting molar's measure of lemgth needed to touch the loand will help clear up some, but not all the questions.

Did AR Performance indicate whether the chamber is the SAAMI chamber or one that will work "better than" the standard chamber?

If so, did the company provide reamer or chamber drawings for the finished barrel?

264 LBC chamber. Non compound throat and .295 neck I believe. I'm pretty sure this chamber was designed to shoot 123 AMAX's, hence why I started testing with that bullet

[molar]

How do you figure neck tension is good?

Inside dimension of neck is .259" after resizing. Further, I can press hard on a loaded round against my reloading bench and the OAL remains unchanged. Same thing after chambering and then measuring.

[LRRPF52]

I've seen a 5 shot group posted by LRRPF52 that was shot with 107 Sierra's out of a Lilja barrel that was literally one ragged hole, but I don't recall what powder and charge he was using.

I found some 120 Nosler BT's at Cabelas today. I have high hopes for these. I don't think I've ever encountered a barrel that would not shoot ballistic tips well. Do you have load data for the 120 BT's using XBR 8028 and CFE 223? Nosler lists 27.5 as max for that bullet, but I can imagine one can go to 28.5

That was witnessed rapid fire with Hornady factory SST or AMAX, don't remember which one, because we had boxes of both.

I think it's pretty clear what your problem is.

[molar]

That was witnessed rapid fire with Hornady factory SST or AMAX, don't remember which one, because we had boxes of both.

I think it's pretty clear what your problem is.

Probably, but nevertheless, I'm going to give it one more go with the 107 and 120 SMK's and 100 and 120 BT's. If I can't get it to group any of those well, I'll either get an 18" JP Supermatch or an 18" Rainier Ultramatch from a shilen blank

I could have sworn that you posted a phenomal group shot with 107 SMK's over at ARFCOM

[JASmith]

264 LBC chamber. Non compound throat and .295 neck I believe. I'm pretty sure this chamber was designed to shoot 123 AMAX's, hence why I started testing with that bullet

Thanks! Knowing those details helps folks refine advice about seating depth.

Apologies for the spelling -- blurry eyes and iPad woes.

Did I miss the post listing the length at land touch in your chamber?

[bwaites]

Probably, but nevertheless, I'm going to give it one more go with the 107 and 120 SMK's and 100 and 120 BT's. If I can't get it to group any of those well, I'll either get an 18" JP Supermatch or an 18" Rainier Ultramatch from a shilen blank

I could have sworn that you posted a phenomal group shot with 107 SMK's over at ARFCOM

This one?

[molar]

This one?

So that was your group then? Was that with 28.5 8208? Also, what OAL? Thanks

[molar]

Thanks! Knowing those details helps folks refine advice about seating depth.

Apologies for the spelling -- blurry eyes and iPad woes.

Did I miss the post listing the length at land touch in your chamber?

I haven't measured distance to lands yet. I don't have a stoney point gauge. I was planning on doing it the old fashioned way using a fired case, a bullet, and a sharpie. All of my cases are sized at this point, so I will have to wait. I sent the barrel maker an email asking for this info. It was posted on his site when the barrels were available, but has since been removed.

ETA: Per manufacturer the 123 AMAX will touch the lands at 2.320". Looks like my mags will allow a maximum OAL of 2.290" or .030" off the lands

[JASmith]

Thanks, the long jump may partly explain your experience.

Have you thought sbout single-shot at the bench to see if a shorter jump makes enough difference to make a difference?

[molar]

Thanks, the long jump may partly explain your experience.

Have you thought sbout single-shot at the bench to see if a shorter jump makes enough difference to make a difference?

You may be right. I've been reading about the AMAX and it appears to have a tangent ogive similar to a Berger VLD and I know from experience that those can be very intolerant to bullet jump. I'm going to load some of the 123 AMAX at 2.290" OAL with 28.5 gr 8208. I'm hopeful that a secant ogive bullet like the 120 SMK or PT will provide better results. Honestly, this is a hunting setup, so if I can obtain good accuracy with the ballistic tips I'll be happy.

[1911man]

Jump may very well be your issue. I was having problems getting the 123 Amaxes to group before I found what jump my barrel likes. Now they are shooting really well for me. My experience with the 120 SMK is that it is a very forgiving bullet. I have several different powder and OAL combos with that bullet that group well out of my gun.